Communication device, control method, and storage medium

ABSTRACT

A communication device establishes a first connection to a first other communication device, establishes, based on the first connection, a second connection to a second other communication device that is connected to the first other communication device, while the first connection has been established, and then performs direct communication with the second other communication device using the second connection. The communication device determines whether an operation mode of the first connection is a mode in which a periodic search for other networks is performed while a network has been established by the first connection. If the operation mode is the mode in which the periodic search is performed, the communication device restricts at least one of establishment of the second connection and switching of a channel in the second connection while the first connection has been established.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a connection control technique inwireless communication.

2. Description of the Related Art

In recent years, wireless LAN communication systems, which arerepresented by IEEE802.11 standard series, are widely used. With awireless LAN, a base station called an access point (hereinafter, AP)and a station (hereinafter, STA) that exists within an area within whicha radio wave of the AP can reach and that is in a wirelessly connectedstate establish a connection, establish a network, and perform wirelesscommunication. Recently, on more occasions, the IEEE802.11n standard isused with which the communication speed can be raised, among theIEEE802.11 standard series.

IEEE802.11n supports a first mode (hereinafter referred to as “HT20”) inwhich operation is performed with a conventional 20-MHz frequencybandwidth, and a second mode (hereinafter referred to as “HT40”) inwhich operation is performed with a 40-MHz frequency bandwidth, which istwice the aforementioned conventional frequency bandwidth, for thepurpose of high-speed communication. However, in an environment in whichthe HT40 is used, there have been cases where a conventional wirelessdevice that does not support IEEE802.11n cannot perform carrier sensing,resulting in a collision between frames. In particular, a 2.4-GHz bandis likely to be affected by surrounding BSSes as compared with a 5-GHzband, since wireless channels are overlapped with one another.

For this reason, in IEEE802.11n, OBSS (Overlapping Basic Service Set)Scan is defined for STAs that operate with the 2.4-GHz HT40. The OBSSScan is a periodic search for surrounding networks performed by a STAoperating with the HT40. Specifically, with the OBSS Scan, surroundingwireless networks that do not support the IEEE802.11n standard andsurrounding wireless networks that do not allow the HT40 are found. Ifthese wireless networks are found, the STA transmits a report to an APof the wireless network that the STA has joined. The AP then switchesits network from a wireless network that supports the HT40 to a wirelessnetwork that supports only the HT20, as necessary. The STA that operateswith the 2.4-GHz HT40 needs to execute this OBSS Scan.

On the other hand, methods have emerged for performing communication notonly with a simple wireless network configuration using conventional APsand STAs, but also in various modes of wireless LAN network. Forexample, Tunneled Direct Link Setup (TDLS) has been proposed as atechnique for communication between STAs that are connected to an AP,using a direct connection (direct link). IEEE Std 802.11-2012 describesa technique of forming a direct connection between wireless STAs bytransmitting and receiving control data for setting TDLS, betweenwireless LAN terminals via an AP. Since each wireless LAN terminaldirectly communicates with a partner terminal by forming a directconnection, communication can be performed that is not affected byrestriction due to the capability of the AP.

With TDLS, a channel for direct communication between STAs is not fixedto a channel (hereinafter referred to as a “base channel”) of a wirelessnetwork configured by the AP and can be switched to another channel(hereinafter referred to as an “off-channel”). As a result, for example,even when the AP operates with a 2.4-GHz band, a STA can directlycommunicate with the partner STA by using a 5-GHz band channel.

In the present situation, the influence of channel switching for directcommunication using TDLS on a connection between an AP and a STA has notbeen considered. For example, when the operation mode of a connectionbetween an AP and a STA is the 2.4-GHz HT40, the STA is required toperiodically execute the OBSS Scan, whereas the problem in switching ofthe channel in the direct communication in this case has not beenexamined.

The present invention has been made in view of the aforementionedproblem, and provides, in a communication system in which a secondconnection is established based on a first connection, connectioncontrol in which the influence of the second connection on the firstconnection is considered.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided acommunication device comprising: a connection unit configured toestablish a first connection to a first other communication device,establish, based on the first connection, a second connection to asecond other communication device that is connected to the first othercommunication device, while the first connection has been established,and perform direct communication with the second other communicationdevice using the second connection; a determination unit configured todetermine whether an operation mode of the first connection is a mode inwhich a periodic search for another network is performed while a networkhas been established by the first connection; and a control unitconfigured to, if the operation mode of the first connection is the modein which the periodic search is performed, control the connection unitso as to restrict at least one of establishment of the second connectionand switching of a channel in the second connection, while the firstconnection has been established.

According to an aspect of the present invention, there is provided acommunication device comprising: a connection unit configured toestablish a first connection to a first other communication device,establish, based on the first connection, a second connection to asecond other communication device that is connected to the first othercommunication device, while the first connection has been established,and perform direct communication with the second other communicationdevice using the second connection; a determination unit configured todetermine whether an operation mode of the first connection is a firstmode in which a periodic search for another network is performed while anetwork has been established by the first connection; and a control unitconfigured to, if the operation mode of the first connection is thefirst mode, and establishment of the second connection or switching of achannel in the second connection is performed, perform control such thatthe operation mode of the first connection is switched to a second modein which the periodic search for another network is not performed whilethe network has been established by the first connection.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments (with reference to theattached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the description, serve to explain the principles of theinvention.

FIG. 1 is a diagram showing an exemplary configuration of a wirelesscommunication system.

FIG. 2 is a block diagram showing an exemplary functional configurationof a STA 101 in Embodiment 1.

FIG. 3 is a sequence chart showing a first example of a processing flowin Embodiment 1.

FIG. 4 is a flowchart showing a first operation example of directcommunication setting control in Embodiment 1.

FIG. 5 is a sequence chart showing a second example of a processing flowin Embodiment 1.

FIG. 6 is a flowchart showing a second operation example of directcommunication setting control in Embodiment 1.

FIG. 7 is a sequence chart showing a third example of a processing flowin Embodiment 1.

FIG. 8 is a flowchart showing a third operation example of directcommunication setting control in Embodiment 1.

FIG. 9 is a sequence chart showing a fourth example of a processing flowin Embodiment 1.

FIG. 10 is a flowchart showing an operation example of the STA 101 atthe time of the OBSS Scan in the fourth example in Embodiment 1.

FIG. 11 is a block diagram showing an exemplary functional configurationof a STA 101 in Embodiment 2.

FIG. 12 is a flowchart showing a first operation example ofcommunication mode decision processing in Embodiment 2.

FIG. 13 is a sequence chart showing an example of a processing flow inthe first operation example in Embodiment 2.

FIG. 14 is a sequence chart showing another example of the processingflow in the first operation example in Embodiment 2.

FIG. 15 is a sequence chart showing still another example of theprocessing flow in the first operation example in Embodiment 2.

FIG. 16 is a flowchart showing a second operation example of thecommunication mode decision processing in Embodiment 2.

FIG. 17 is a flowchart showing a third operation example of thecommunication mode decision processing in Embodiment 2.

FIG. 18 is a sequence chart showing an example of a processing flow inthe third operation example in Embodiment 2.

FIG. 19 is a sequence chart showing another example of the processingflow in the third operation example in Embodiment 2.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will now be described in detailwith reference to the drawings. It should be noted that the relativearrangement of the components, the numerical expressions and numericalvalues set forth in these embodiments do not limit the scope of thepresent invention unless it is specifically stated otherwise.

Note that a description will be given below of the case where a wirelessLAN conforming to the IEEE802.11 standard series, in particular awireless LAN conforming to the IEEE802.11n standard is used. However,the following embodiments describe examples, and the present inventionis not limited thereto and is also applicable in the case where othersimilar systems are used. That is to say, the following discussion isapplicable to any system in which a communication device establishes afirst connection between the communication device and a first othercommunication device, and establishes, based on the first connection, asecond connection between the communication device and a second othercommunication device that is connected to the communication device andthe first other communication device. Note that the communication deviceand the second other communication device in this case correspond toterminals (STAs) in a wireless LAN, the first other communication devicecorresponds to a base station (AP) in the wireless LAN, the firstconnection is a connection between an AP and a STA, and the secondconnection is a direct connection between STAs by means of TDLS, forexample.

Exemplary Configuration of Wireless Communication System

An exemplary configuration of a wireless communication system in theembodiments described below is shown in FIG. 1. A STA 101 is a terminal(STA) in a wireless LAN that conforms to the IEEE802.11n standard. TheSTA 101 has joined a wireless network 104 formed by a base station (AP)102 in the wireless LAN. The AP 102 is a base station (access point) ofthe wireless LAN that forms the wireless network 104. The STA 103 is aSTA that has joined the wireless network 104. The wireless network 104is a 2.4-GHz wireless LAN network, for example, generated by the AP 102,and STAs, namely the STA 101 and the STA 103 have joined the wirelessnetwork 104 in the example in FIG. 1.

If the wireless network 104 is a wireless network in which communicationcan be performed in the first mode (HT40), the STA 101 joins thewireless network with the HT40. Furthermore, if the STA 101 has joinedthe 2.4-GHz wireless network with the HT40, the STA 101 periodicallyexecutes OBSS (Overlapping Basic Service Set) Scan in conformity to theIEEE802.11n standard. The OBSS Scan is executed for 1ch to 11ch.

Note that the HT40 is an operation mode of a connection between a STAand an AP, and is a mode (e.g., 2.4-GHz HT40) that requires a periodicsearch for other networks while the connection has been established.Here, as mentioned above, the HT40 is an operation mode in whichcommunication is performed using a 40-MHz bandwidth for the purpose ofhigh-speed communication in IEEE802.11n. Other operation modes of aconnection between a STA and an AP include a conventional operation mode(HT20) in which operation is performed with a 20-MHz frequencybandwidth. Here, the HT20 is an operation mode that does not require theperiodic search for other networks. Note that the HT40 is a mode inwhich higher-speed communication than with the HT20 is possible.

On the other hand, if the wireless network 104 is a wireless network inwhich communication with the HT40 cannot be performed and onlycommunication with the HT20 is possible, the STA 101 joins the wirelessnetwork with the HT20 and does not execute the OBSS Scan.

Outline

Prior to the description of the embodiments of the present invention, anoutline of the technique will be described. First, in order to smooththe following description of the embodiments, an example will bedescribed of the influence that a direct connection between a first STAand a second STA may possibly exert on an AP-STA connection between thefirst STA and an AP.

The case will be examined in which the STA 101, while executing the OBSSScan, receives a request to switch a channel for direct communicationfrom another STA, namely a STA 103, to which the STA 101 has establisheda direct connection. In this case, if the STA 101 switches the channelin accordance with the received request, the STA 101 needs to againexecute the OBSS Scan that was in the middle of execution, afterswitching the channel. However, at this time, a problem may possiblyarise regarding the channel to which the STA 101 is to return. Forexample, consider the case where the channel (base channel) of thewireless network formed by the AP is 3ch, the channel (off-channel) fordirect communication between STAs is 36ch, and the search is performedon the OBSS Scan for 1ch to 11ch in order. If the STA 101 switches itschannel to 36ch while scanning 5ch with the OBSS Scan, there are caseswhere the STA 101, when returning from the off-channel, returns to 3ch,which is the base channel, rather than to the channel on which the STA101 was performing the OBSS Scan. For this reason, in some cases, theSTA 101 does not execute the OBSS Scan for 5ch and subsequent channels.There are also cases where the STA 101, after similarly switching thechannel, returns to 6ch, which is to be scanned next, even though theSTA 101 was in the middle of scanning of 5ch, and does not scan 5chwithin a prescribed time period.

If the STA 101 successively receives channel switching requests duringthe OBSS Scan, the STA 101 successively moves to channels other than thebase channel while receiving these requests, and accordingly there arecases where the STA 101 cannot execute the OBSS Scan for a while. Here,the OBSS Scan needs to be executed at an interval designated by the AP102. For this reason, such behavior of the STA 101 is not allowed insome cases. As described above, if a direct connection is establishedand, in particular, switching of the channel occurs when the OBSS Scanneeds to be executed, there are cases where processing becomescomplicated and the OBSS Scan cannot be stably performed.

Therefore, a communication device according to the following embodimentsperforms communication control for handling these problems.Specifically, a communication device (STA 101) checks whether anoperation mode of a first connection to a first other communicationdevice (AP 102) is a first mode in which the periodic search for othernetworks is performed while the connection has been established, such asthe 2.4-GHz HT40. If the operation mode of the first connection is thefirst mode, the communication device performs control so as not toperform at least one of establishment of a second connection to a secondother communication device (a STA that is to be a partner device of adirect connection) and switching of the channel in the secondconnection, for example. Furthermore, if establishment of the secondconnection or switching of the channel in the second connection occurswhile the operation mode of the first connection is the aforementionedfirst mode, the communication device may switch the operation mode ofthe first connection to a mode in which the periodic search for othernetworks is not performed.

With this configuration, establishment of the second connection (adirect connection between STAs) and switching of the channel in thesecond connection are restricted, depending on the cases. That is tosay, at least one of establishment of the second connection andswitching of the channel is performed only when, for example, theoperation mode of the first connection (a connection between a STA andan AP) is not a mode in which the periodic search for other networks isperformed, such as the 2.4-GHz HT40. For this reason, the influence ofthe second connection on the first connection can be suppressed.

In the following embodiments, the above processing and a configurationof a communication device that performs this processing will bedescribed in detail.

Embodiment 1

In the present embodiment, when the operation mode of the firstconnection between the STA 101 and the AP 102 is the 2.4-GHz HT40, theSTA 101 restricts the second connection (direct connection) to the STA103, thereby preventing switching of a channel in the second connection.The STA 101 thereby prevents switching of the channel in the secondconnection from occurring during the OBSS Scan in the first connection,and prevents a malfunction of channel control.

Functional Configuration of STA 101

FIG. 2 is a block diagram showing an exemplary functional configurationof the STA 101 according to the present embodiment. The STA 101 has anRF control unit 201, a terminal station control unit 202, a directcommunication control unit 203, a direct communication setting controlunit 204, an application control unit 205, and a storage unit 206, forexample. One or more of these functional units can be implemented by oneor more processors (CPUs) executing a computer program that can bestored in a storage medium, such as a memory (RAM or ROM).

The RF control unit 201 is configured to include an antenna fortransmitting or receiving a wireless signal from/to other wireless LANcommunication devices, a circuit, and a program for controlling them.The terminal station control unit 202 is configured to include hardwareand a program for controlling the RF control unit 201 and functioning asa wireless LAN STA (terminal), for example. The terminal station controlunit 202 performs control such that the STA 101 joins, as a terminal,the wireless network 104 and communicates with the AP 102.

The direct communication control unit 203 is configured to includehardware and a program for controlling the RF control unit 201, anddirectly communicating with the STA 103 without via the AP 102 afterestablishing, via the AP 102, a direct connection to the STA 103, forexample. The direct communication setting control unit 204 is configuredto include a program for determining setting control related to directcommunication when a request to establish a direct connection is givenfrom the STA 103 via the AP 102, for example. The specific control ofthe direct communication setting control unit 204 will be describedlater using FIGS. 4 and 6.

The application control unit 205 is configured to include software andhardware for controlling an application that operates on the STA 101,for example. The STA 101 communicates with communication devices inother wireless LANs in accordance with an instruction of the applicationcontrol unit 205. The storage unit 206 is constituted by a ROM and a RAMfor saving a program and data by which the STA 101 operates, forexample.

Processing Flow

In the present embodiment, the STA 101 checks whether the operation modeof the first connection to the AP 102 is a mode in which the periodicsearch for other networks is performed while the connection has beenestablished, such as the 2.4-GHz HT40. If the operation mode of thefirst connection is the first mode, the STA 101 performs control so asnot to perform at least one of establishment of the second connection(direct connection) to the STA 103 and switching of the channel in thesecond connection, for example. A flow of this processing will bedescribed below using FIGS. 3 to 10.

Processing Example 1

FIG. 3 shows a first example of a processing flow in the presentembodiment. In this example, the STA 101 receives a TDLS DiscoveryRequest from the STA 103 via the AP 102. The TDLS Discovery Request is aframe that is defined in the IEEE802.11 standard and is transmitted inorder to find other STAs with which direct communication can beperformed.

Initially, the STA 103 broadcasts a discovery request (TDLS DiscoveryRequest) for searching for STAs with which direct communication can beperformed. The AP 102, upon receiving this TDLS Discovery Request,broadcasts the received signal. Thereafter, the TDLS Discovery Requesttransmitted by the AP 102 is received by the STA 101 (S301). The STA101, upon receiving the TDLS Discovery Request, executes directcommunication setting control processing for determining whether the STA101 is in a state of being able to establish a direct connection (S302).

FIG. 4 shows a processing flow of the direct communication settingcontrol in this case. The processing in FIG. 4 is executed by the directcommunication setting control unit 204.

In this processing, the direct communication setting control unit 204determines whether the STA 101 has joined the wireless network 104 withthe 2.4-GHz HT40 (S401). If the STA 101 has joined the wireless network104 with the 2.4-GHz HT40 (YES in S401), the direct communicationsetting control unit 204 determines not to response to the received TDLSDiscovery Request (S402). That is to say, the direct communicationsetting control unit 204 determines not to respond to the TDLS DiscoveryRequest if the operation mode of the connection between the STA 101 andthe AP 102 is a mode in which the periodic search for other networks isperformed. Establishment of a direct connection to the STA 103 isthereby restricted, and it is possible to prevent the direct connectionfrom affecting the periodic search for other networks in the connectionbetween the STA 101 and the AP 102.

On the other hand, if it is determined that the STA 101 has not joinedthe wireless network 104 with the 2.4-GHz HT40 (NO in S401), the directcommunication setting control unit 204 determines to respond to thereceived TDLS Discovery Request (S403). Note that the response signal inthis case is a TDLS Discovery Response. This is because, in this case,the STA 101 does not need to periodically search for other networks, andaccordingly no problem arises even if a direct connection is establishedand the channel is changed.

Returning to FIG. 3, if it is determined that the TDLS DiscoveryResponse is to be transmitted, the STA 101 responds by transmitting theTDLS Discovery Response to the STA 103 via the AP 102 (S303). On theother hand, if it is determined in step S402 that a response is not tobe given, the STA 101 does not transmit the TDLS Discovery Response instep S303.

With the above processing, if the STA 101 is connected to the AP 102with the 2.4-GHz HT40, the other STA, namely the STA 103 does notreceive the TDLS Discovery Response from the STA 101. For this reason,the STA 103 determines that the STA 101 is a STA which cannot executeTDLS. On the other hand, in the case of the HT20, the STA 103 receivesthe TDLS Discovery Response from the STA 101, and accordingly candetermine that the STA 101 is a STA which can execute TDLS.

Processing Example 2

FIG. 5 shows a second example of a processing flow in the presentembodiment. In this example, the STA 101 receives a TDLS Setup Requestfrom the STA 103 via the AP 102. A TDLS Setup Request is a frame forgiving a request that is defined in the IEEE802.11 standard and is forestablishing a direct connection.

Initially, the STA 103 transmits a TDLS Setup Request to the STA 101 viathe AP 102 in order to establish a direct connection to the STA 101(S501). The STA 101, upon receiving the TDLS Setup Request, executesdirect communication setting control processing in order to determinewhether the STA 101 is in a state of being able to execute directcommunication (S502).

FIG. 6 shows a processing flow of the direct communication settingcontrol in this case. The processing in FIG. 6 is executed by the directcommunication setting control unit 204, as in the processing example 1.

In this processing, the direct communication setting control unit 204determines whether the STA 101 has joined the wireless network 104 withthe 2.4-GHz HT40, as in step S401 in the processing example 1 (S601). Ifthe STA 101 has joined the wireless network 104 with the 2.4-GHz HT40(YES in S601), the direct communication setting control unit 204 decidesto refuse the received TDLS Setup Request (S602). That is to say, if theoperation mode of the connection between the STA 101 and the AP 102 is amode in which the periodic search for other networks is performed, thedirect communication setting control unit 204 refuses the TDLS SetupRequest. In this case, the STA 101 designates REFUSED (=1) as a StatusCode of the TDLS Setup Response frame and transmits it. Establishment ofa direct connection to the STA 103 is thereby restricted, and it ispossible to prevent the direct connection from affecting the periodicsearch for other networks in the connection between the STA 101 and theAP 102. Note that the Status Code designated here may be any value forrefusing establishment of a direct connection, and other values may beused as long as the values are other than SUCCESS (=0). Furthermore, theSTA 101 may communicate the refusal of establishment of a connection bynot responding, rather than by responding using the TDLS Setup Response.

On the other hand, if it is determined that the STA 101 has not joinedthe wireless network 104 with the 2.4-GHz HT40 (NO in S601), the directcommunication setting control unit 204 determines not to refuse thereceived TDLS Setup Request, and to respond thereto (S603). That is tosay, in this case, the STA 101 designates SUCCESS (=0) as a Status Codeof the TDLS Setup Response frame and transmits it.

Returning to FIG. 5, the STA 101, after executing the aforementioneddirect communication setting control, transmits the TDLS Setup Responsecontaining the Status Code corresponding to the determination to the STA103 via the AP 102 (S503). If the STA 103 receives the TDLS SetupResponse with the Status Code that is SUCCESS, the STA 103 transmitsTDLS Setup Confirm (S504), and a direct connection between the STA 101and the STA 103 is thereby established. On the other hand, if the StatusCode is other than SUCCESS, e.g., if the Status Code is REFUSED, the STA103 does not transmit the TDLS Setup Confirm in step S504. Accordingly,in this case, a direct connection is not established.

As described above, in the processing examples 1 and 2, even if the STA101 receives a request to search for a partner device of a directconnection or a request to establish a direct connection, the STA 101does not respond to the request or refuses it, in order to restrict thesetting of the direct communication. With this configuration, the STA101 does not establish a direct connection to other STAs when the STA101 has joined the wireless network 104 with the 2.4-GHz HT40. A directconnection is thereby not established, and accordingly switching of thechannel in the direct connection does not occur. That is to say, channelswitching of TDLS (TDLS channel switching) does not occur when the STA101 has joined the wireless network 104 with the 2.4-GHz HT40, i.e.,when the STA 101 needs to execute the OBSS Scan. Therefore, the OBSSScan can be prevented from becoming unstable due to switching of thechannel.

Processing Example 3

FIG. 7 shows a third example of a processing flow in the presentembodiment. In this example, the STA 101 receives a request (TDLSChannel Switch Request) to switch the channel from the STA 103 via theAP 102. A TDLS Channel Switch Request is a frame that is defined in theIEEE802.11 standard and is for giving a request to switch the channelfrom the base channel to the off-channel. Note that the TDLS ChannelSwitch Request is transmitted after a direct connection by means of TDLSis established.

That is to say, in this example, a direct connection is firstestablished between the STA 101 and the STA 103. Specifically, the STA101, upon receiving the TDLS Setup Request from the STA 103, respondsusing a TDLS Setup Response with a Status Code that is SUCCESS (=0)(S702). The STA 103, upon receiving the TDLS Setup Response with theStatus Code that is SUCCESS, transmits TDLS Setup Confirm (S703). Adirect connection between the STA 101 and the STA 103 is therebyestablished.

After the direct connection is established, the STA 103 directlytransmits a TDLS Channel Switch Request to the STA 101 without via theAP 102 before transmitting data, in order to switch the channel (S704).The STA 101, upon receiving the TDLS Channel Switch Request, executesdirect communication setting control processing (S705).

FIG. 8 shows a processing flow of the direct communication settingcontrol in this case. The processing in FIG. 8 is executed by the directcommunication setting control unit 204, as in the processing examples 1and 2.

In this processing, the direct communication setting control unit 204initially determines whether the STA 101 has joined the wireless network104 with the 2.4-GHz HT40, as in the processing examples 1 and 2 (S801).If the STA 101 has joined the wireless network 104 with the 2.4-GHz HT40(YES in S801), the direct communication setting control unit 204 decidesto refuse the request to switch the channel (S802). That is to say, ifthe operation mode of the connection between the STA 101 and the AP 102is a mode in which the periodic search for other networks is performed,the direct communication setting control unit 204 refuses the TDLSChannel Switch Request. In this case, the STA 101 designates REFUSE (=1)as a Status Code of the TDLS Channel Switch Response and transmits it,for example. Switching of the channel in the direct connection to theSTA 103 is thereby restricted, and it is possible to prevent the directconnection from affecting the periodic search for other networks in theconnection between the STA 101 and the AP 102. Note that the Status Codedesignated here may be any value for refusing the channel switchingrequest, and the channel switching request may be refused bysubstituting a value other than SUCCESS (=0) for the Status Code.Furthermore, the refusal of switching of the channel may be communicatedby not responding to the channel switching request. Note that adescription will be given below of the case where a response is givenwith REFUSE (=1) designated as the Status Code when the channelswitching request is refused.

Note that, on the other hand, if the STA 101 has not joined the wirelessnetwork 104 with the 2.4-GHz HT40 in step S801 (NO in S801), the directcommunication setting control unit 204 decides to accept the channelswitching request (S803). In this case, the STA 101 designates SUCCESS(=0) as a Status Code of the TDLS Channel Switch Response and transmitsit.

Returning to FIG. 7, the STA 101, after executing the aforementioneddirect communication setting control, transmits the TDLS Channel SwitchResponse containing the Status Code corresponding to the determination,to the STA 103 via the AP 102 (S706). If the STA 103 receives the TDLSChannel Switch Response with the Status Code that is SUCCESS (=0), theSTA 101 and the STA 103 switch their channel to the off-channel inconformity to the IEEE802.11 standard. Then the STA 101 and the STA 103start direct communication. On the other hand, if the STA 103 receivesthe TDLS Channel Switch Response with the Status Code that is REFUSE(=1), switching of the channel is not performed and the processing isfinished in this state.

With this configuration, in this example, switching of the channel in adirect connection is not performed when the STA 101 has joined thewireless network 104 with the 2.4-GHz HT40. For this reason, it ispossible to prevent the OBSS Scan operation from becoming unstable as aresult of switching the channel.

In this example, unlike in the above processing examples 1 and 2, evenwhen the STA 101 has joined the wireless network 104 with the 2.4-GHzHT40, the STA 101 can establish a direct connection to the STA 103 anddirectly communicate therewith without via the AP 102. Communicationoverhead caused due to communicating via the AP 102 can thereby bereduced. Furthermore, communication beyond the communication capabilityof the wireless network 104 can be performed between the STA 101 and theSTA 103. For example, even when the AP 102 supports only 64QAM as amodulation method in the 2.4-GHz HT40, 256QAM can be used as amodulation method in the communication between the STA 101 and the STA103, and high-speed communication can be realized.

Processing Example 4

Unlike the above processing examples 1 to 3, this example will describethe case where a direct connection operation is restricted while theOBSS Scan is actually being performed, rather than that the directconnection operation is restricted depending on whether thecommunication device has joined the wireless network 104 with the2.4-GHz HT40. That is to say, in this example, switching of the channelin a direct connection is allowed except during the execution period ofthe OBSS Scan that is affected by the switching of the channel by adirect connection in some cases. Note that the processing describedbelow is performed when the STA 101 has joined the wireless network 104with the 2.4-GHz HT40, and the STA 101 may also determine whether theoperation mode is the 2.4-GHz HT40, prior to the processing.

FIG. 9 shows a processing flow in this example. Note that it is assumedin this example that the base channel of the wireless network 104 is3ch, and the off-channel to which the channel of the STA 101 and the STA103 may possibly be switched is 9ch. It is also assumed in this examplethat a direct connection has already been established between the STA101 and the STA 103, and the STA 101 periodically receives the TDLSChannel Switch Request from the STA 103. Note that, although therestriction on switching of the channel during an OBSS Scan period willbe described below based on the premise that a direct connection hasbeen established, this example is not limited thereto. That is to say,for example, if a request to search for a partner device of a directconnection or a request to establish a direct connection is given fromthe STA 103 during the OBSS Scan period, the STA 101 may be configurednot to respond to these requests, or may refuse these requests.Furthermore, in this case, the STA 101 accepts these requests only ifthe request to search for a partner device of a direct connection or therequest to establish a direct connection is given from the STA 103during a time period other than the OBSS Scan period, for example.

It is also assumed that the STA 101 starts a series of processing forperforming the OBSS Scan at the timing of step S906, and has not yetstarted the OBSS Scan at the time of the start in FIG. 9, i.e., at thetime of step S901. Steps S900, S912, S915, and S923 indicate Beaconsthat are periodically broadcast by the AP 102 over the base channel.Note that, although these Beacons may possibly be received by the STA101 and the STA 103, FIG. 9 only schematically expresses it, and theBeacons do not necessarily need to be transmitted and received at theshown timings.

In this processing, initially, the STA 103 transmits a TDLS ChannelSwitch Request to the STA 101 (S901). The STA 101, upon receiving theTDLS Channel Switch Request, accepts this request since it is not yetthe timing of starting the OBSS Scan. That is to say, the STA 101designates SUCCESS as a Status Code and transmits a TDLS Channel SwitchResponse (S902). The STA 101, upon transmitting the TDLS Channel SwitchResponse, switches its channel to the off-channel (S903). The STA 103,upon receiving the TDLS Channel Switch Response, switches its channel tothe off-channel (S904). Note that the order of the processing in stepsS903 and S904 may possibly be reversed depending on the timings oftransmitting and receiving signals to/from the STA and the time taken toswitch the channel. Thereafter, the STA 103 transmits data to the STA101 over the off-channel (S905).

The STA 101 performs direct communication setting control simultaneouslywith the timing of starting the OBSS Scan (S906). Specifically, the STA101 configures a setting so as to prohibit switching of the channel ofTDLS during the OBSS Scan period. Thereafter, until a setting isconfigured so as to allow channel switching, even if the STA 101receives the TDLS Channel Switch Request, the STA 101 operates so as torefuse or ignore it.

The STA 101, upon configuring a setting so as to prohibit channelswitching, transmits a TDLS Channel Switch Response to the STA 103 overthe off-channel in order to stop communication with the STA 103 over theoff-channel (S907). Then, the STA 101 again switches its channel to thebase channel in accordance with the transmission of this TDLS ChannelSwitch Response (S908). The STA 103 switches its channel to the basechannel in accordance with reception of the TDLS Channel Switch Response(S909). Note that the order of steps S908 and S909 may possibly bereversed for the same reason as that in steps S903 and S904.

The STA 101, upon returning its channel to the base channel, starts theOBSS Scan. Specifically, the STA 101 scans (searches) 1ch to 11ch forother networks in order (S910, S911, S914, S918, S919). Note that FIG. 9does not show the scan of 5ch to 10ch, for the sake of simplification.

Here, assume that a TDLS Channel Switch Request is transmitted from theSTA 103 over 3ch, which is the base channel, while the STA 101 isscanning 2ch. However, in this case, the STA 101 is scanning 2ch andaccordingly does not receive this TDLS Channel Switch Request (S913).Assume that, thereafter, a TDLS Channel Switch Request is transmittedfrom the STA 103 over 3ch, which is the base channel, while the STA 101is scanning 3ch. In this case, since the channel that the STA 101 isscanning is 3ch, the STA 101 receives this TDLS Channel Switch Request(S916). However, since the STA 101 configures a setting so as toprohibit channel switching in step S906, the STA 101 transmits a TDLSChannel Switch Response in which REFUSED is designated as a Status Code(S917). Note that what is important here is that the STA 101 does notswitch its channel to the off-channel, and other methods may also beused. For example, the STA 101 may be configured to ignore the TDLSChannel Switch Request and not to respond thereto.

The STA 101, upon completing the scan up to 11ch, returns to 3ch, whichis the base channel (S920). Then the STA 101, after returning to 3ch,notifies the AP 102 of a result of the OBSS Scan using a 20/40 BSSCoexistence Management frame (S921). Note that the 20/40 BSS CoexistenceManagement frame is a frame that is defined in the IEEE802.11n standardand is for notifying a connected AP of information regarding surroundingBSSes.

The STA 101, after notifying the AP 102 of the scan result, performsdirect communication setting control (S922). Specifically, the STA 101removes prohibition of channel switching that is set in step S906, andconfigures a setting so as to permit channel switching of TDLS. Afterthe permission of channel switching is set in step S922, if the STA 101receives a TDLS Channel Switch Request from the STA 103 (S924), the STA101 accepts this request. That is to say, in this case, the STA 101transmits a TDLS Channel Switch Response in which SUCCESS is designatedas a Status Code to the STA 103 (S925). In the subsequent processing, asin steps S903 to S905, the STA 101 and the STA 103 switch their channelto the off-channel and exchange data through direct communication.

Subsequently, processing at the time of the OBSS Scan of the STA 101 inthis example will be described using a flowchart in FIG. 10. Thisprocessing is executed at the timing of starting the OBSS Scan. Notethat the time interval of the OBSS Scan execution is designated by aProbe Response transmitted by the AP 102. More specifically, this timeinterval is designated by a BSS Channel Width Trigger Scan Interval inthe information of an OBSS Scan Parameters element contained in theProbe Response.

Initially, when the timing of starting the OBSS Scan comes, the STA 101configures a setting so as to prohibit channel switching of TDLS(S1001). This is processing similar to the processing described in theabove description of step S906. The STA 101, after configuring thesetting so as to prohibit channel switching of TDLS, refuses thereceived TDLS Channel Switch Request or does not respond thereto.

Next, the STA 101 determines whether the channel at which the STA 101 iscurrently staying is the base channel (S1002). At this time, if the STA101 is staying at the base channel (YES in S1002), the processingproceeds to step S1005. On the other hand, if the STA 101 is not stayingat the base channel due to channel switching, i.e., the STA 101 isstaying at the off-channel (NO in S1002), the STA 101 transmits a TDLSChannel Switch Response (S1003). The STA 101 thereby notifies the STA103 of switching of the channel to the base channel. This processingcorresponds to step S907 described above. After this notification, theSTA 101 returns to the base channel (S1004). This processing correspondsto step S908 described above.

The STA 101, upon returning to the base channel, executes scan of 1ch to11ch in order (S1005). This processing corresponds to steps S913, S914,S917, S922, and S923 described above. Then the STA 101, upon completingthe scan, notifies the AP 102 of a scan result using a 20/40 BSSCoexistence Management frame (S1006). This processing corresponds tostep S921 described above.

The STA 101, after notifying the AP 102 of the scan result, sets a statewhere channel switching of TDLS is permitted that has been in aprohibited state due to the setting in step S1001 (S1007). Thisprocessing corresponds to step S922 described above, and after thissetting, if the STA 101 receives the TDLS Channel Switch Request, theSTA 101 responds so as to accept this request.

With this configuration, even when the STA 101 has joined the wirelessnetwork 104 with the 2.4-GHz HT40, the STA 101 can execute stable OBSSScan by prohibiting channel switching of TDLS during a time periodduring which the OBSS Scan is executed. In this example, unlike in theabove processing examples 1 to 3, even if the frequency band of thewireless network 104 is a 2.4-GHz band, the STA 101 can join thewireless network 104 with the HT40 while establishing a directconnection. Since the STA 101 can switch the channel in a directconnection unless the STA 101 is executing the OBSS Scan, the STA 101can directly communicate with other STAs over the off-channel inaccordance with the situation, while communicating with the AP with theHT40 that enables high-speed communication.

Note that, although a setting is configured in step S922 so as to permitchannel switching of TDLS in the above description, the STA 101 may alsoconfigure a setting so as to prohibit channel switching of TDLS afterthis setting, in accordance with the situation excluding the OBSS Scan.For example, if the STA 101 receives a data packet from the AP 102, orif the STA 101 needs to transmit data to the AP 102, channel switchingduring this time period may be prohibited.

In the description of this example, although the time period duringwhich channel switching of TDLS is prohibited is started at the timingof starting the OBSS Scan, the prohibition period may start at anearlier timing than the timing of starting the OBSS Scan. For example,the time period during which channel switching is prohibited may startat a timing of the AP 102 transmitting a Beacon immediately before thetiming of starting the OBSS Scan. It is thereby possible to preventunnecessary switching between the base channel and the off-channel fromoccurring when the OBSS Scan is started immediately after the channel ofTDLS is switched.

In this example, as described regarding steps S908 and S1004, the STA101 returns to the base channel if the timing of starting the OBSS Scancomes while the STA 101 is staying at the off-channel. However, the STA101 may start the OBSS Scan without necessarily returning to the basechannel. For example, the STA 101 may move to 1ch from the off-channel,namely 9ch, without returning to the base channel, namely 3ch, and mayperform the OBSS Scan from 1ch in order. However, as a result oftemporarily moving from the off-channel to the base channel beforestarting the OBSS Scan, processing for moving among the channels for theOBSS Scan is facilitated. That is to say, with this operation, the STA101 can easily return to the original base channel by causing the STA101 to always return, after executing the OBSS Scan, to the channel atwhich the STA 101 was staying before starting the OBSS Scan.

As described above, in the present embodiment, the STA 101 restrictsestablishment of a direct connection to the STA 103 and switching of thechannel when the operation mode of a connection to the AP 102 is a mode(e.g., 2.4-GHz HT40) in which the OBSS Scan is executed. It is therebypossible to stabilize the OBSS Scan operation.

Embodiment 2

In the present embodiment, the STA 101 performs control so as to changethe operation mode of the first connection if the second connection tothe STA 103 is established or the channel is switched when the operationmode of the first connection to the AP 102 is the 2.4-GHz HT40. That isto say, if the second connection is established or the channel isswitched, the STA 101 switches the operation mode such that theoperation mode of the first connection is a mode in which the periodicsearch for other networks, such as the OBSS Scan, is not performed. Itis thereby possible to prevent the OBSS Scan from being executed whenchannel switching occurs, and to avoid execution of an unstable OBSSScan.

Functional Configuration of STA 101

FIG. 11 is a block diagram showing an exemplary functional configurationof the STA 101 according to the present embodiment. The STA 101 has anRF control unit 201, a terminal station control unit 202, a directcommunication control unit 203, an application control unit 205, astorage unit 206, a communication mode deciding unit 1101, and an UIcontrol unit 1102, for example. Note that the RF control unit 201, theterminal station control unit 202, the direct communication control unit203, the application control unit 205, and the storage unit 206 aresimilar to the functional units that are given the same referencenumerals in FIG. 2, and accordingly a description thereof will beomitted.

The communication mode deciding unit 1101 is configured to include aprogram for deciding to join the wireless network 104 with the HT20 orto join it with the HT40, for example. Processing of the communicationmode deciding unit 1101 is executed when receiving a TDLS Setup Requestand TDLS Teardown, and the details thereof will be described later usingFIGS. 12 and 16, respectively. The UI (User Interface) control unit 1102is a UI with which a user (not shown) of the STA 101 operates the STA101, and is configured to include hardware and a program that constitutethe UI, for example. With the UI control unit 1102, the user can setwhether to activate or inactivate TDLS of the STA 101.

Processing Flow

In the present embodiment, the STA 101, when, for example, establishinga direct connection to the STA 103, checks whether the operation mode ofthe first connection to the AP 102 is a first mode in which the periodicsearch for other networks is performed while the connection has beenestablished, such as the 2.4-GHz HT40. If, for example, the operationmode of the first connection is the first mode, the STA 101 performscontrol so as to change the operation mode to a mode in which theperiodic search for other networks is not performed while the connectionhas been established, such as the HT20. A flow of this processing willbe described below using FIGS. 12 to 19.

Processing Example 1

FIG. 12 shows a first example of a processing flow in the presentembodiment. FIG. 12 is a flowchart showing a flow of communication modedecision processing of the communication mode deciding unit 1101 whenthe STA 101 receives a TDLS Setup Request. This processing is executedif a TDLS Setup Request is received from the STA 103.

The communication mode deciding unit 1101 initially determines whetheror not the STA 101 has joined the wireless network 104 with the 2.4-GHzHT40 (S1201). If the STA 101 has joined the wireless network 104 in anoperation mode other than the 2.4-GHz HT40 (NO in S1201), the STA 101does not need to execute the OBSS Scan. For this reason, the STA 101transmits a TDLS Setup Response as-is (S1204) and establishes a directconnection to the STA 103.

On the other hand, if it is determined that the STA 101 has joined thewireless network 104 with the 2.4-GHz HT40 (YES in S1201), the STA 101transmits a Reassociation Request to the AP 102 (S1202). At this time,Supported Channel Width Set in an HT Capabilities Info field of an HTCapabilities element that is added to the Reassociation Request is setto 0. That is to say, the STA 101 gives the AP 102 a request to rejointhe wireless network 104 with the HT20.

The STA 101, upon transmitting the Reassociation Request, receives theReassociation Response transmitted from the AP 102 (S1203). A connectionwith the HT20 is thereby established, and execution of the OBSS Scanbecomes unnecessary. Thereafter, if the connection to the AP 102 is in asecurity mode such as WPA-PSK or WPA2-PSK, the STA 101 may execute keyexchange processing with the AP 102.

Next, the STA 101 transmits, to the STA 103, a TDLS Setup Response as aresponse to the TDLS Setup Request received before the determination instep S1201 (S1204). The STA 101 then waits for reception of TDLS SetupConfirm as a response to the TDLS Setup Response from the STA 103 for afixed time period (S1205). At this time, if the TDLS Setup Confirm isreceived (YES in S1205), it means that a direct connection has beenestablished, and accordingly the processing is finished.

On the other hand, if the TDLS Setup Confirm is not received (NO inS1205), it is determined that the received TDLS Setup Request is timedout at the STA 103. The STA 101 then transmits a TDLS Setup Request tothe STA 103 in order to establish a direct connection (S1206). Thesubsequent processing is similar to the usual TDLS Setup processing, anda direct connection is thereby established. As a result of theprocessing in these steps S1205 and S1206, the STA 101 can establish adirect connection to the STA 103 even if the processing in steps S1201to S1203 takes time and the TDLS Setup Request of the STA 103 is timedout.

A flow of the above processing in the overall wireless communicationsystem will be described using sequence charts in FIGS. 13 to 15. FIGS.13 and 14 show processing flows in the case where the STA 101 has joinedthe wireless network 104 with the 2.4-GHz HT40. On the other hand, FIG.15 shows a processing flow in the case where the STA 101 has joined thewireless network 104 in the 2.4-GHz HT20. FIG. 13 shows a processingflow in the case where the TDLS Setup Request of the STA 103 is nottimed out, and FIG. 14 shows a processing flow in the case where it istimed out.

In FIG. 13, initially, the STA 103 transmits a TDLS Setup Request to theSTA 101 (S1301). The STA 101, upon receiving the TDLS Setup Request,executes the determination in step S1201 using the communication modedeciding unit 1101. In FIG. 13, since the STA 101 has joined thewireless network 104 with the 2.4-GHz HT40, the STA 101 transmits aReassociation Request to the AP 102 (S1202, S1302). The STA 101 therebygives a request to join the wireless network 104 with the HT20.Thereafter, a Reassociation Response is transmitted from the AP 102 tothe STA 101 (S1303). Then the STA 101 transmits, to the STA 103, a TDLSSetup Response as a response to step S1301 (S1304). The STA 103, uponreceiving the TDLS Setup Response, transmits TDLS Setup Confirm (S1305).The STA 101 can thereby establish a direct connection to the STA 103while joining the wireless network 104 in the 2.4-GHz HT20.

FIG. 14 shows an exemplary case where the TDLS Setup Response in stepS1304 in FIG. 13 is timed out at the STA 103. Processing in steps S1401to S1404 is similar to the processing in steps S1301 to S1304, andaccordingly a description thereof will be omitted. If a timeout occursin step S1404, the STA 103 ignores the TDLS Setup Response and does nottransmit the TDLS Setup Confirm in step S1305. In this case, the STA 101executes the processing in step S1206 in accordance with thedetermination in step S1205 in FIG. 12. That is to say, if the TDLSSetup Confirm is not returned (NO in S1205), the STA 101 transmits theTDLS Setup Request to the STA 103 (S1206, S1405). The STA 103 transmitsthe TDLS Setup Response to the STA 101 in response to reception of theTDLS Setup Request (S1406). The STA 101 then transmits the TDLS SetupConfirm to the STA 103 in response to reception of the TDLS SetupResponse. A direct connection between the STA 101 and the STA 103 isthereby established. As a result, even if the TDLS Setup Request of theSTA 103 is timed out, the STA 101 can establish a direct connection tothe STA 103 while joining the wireless network 104 in the 2.4-GHz HT20.

FIG. 15 shows a processing flow in the case where the STA 101 has joinedthe wireless network 104 in the 2.4-GHz HT20. In this case as well, uponthe STA 103 transmitting the TDLS Setup Request to the STA 101 (S1501),the determination in step S1201 is executed in the STA 101, as in theexample in FIG. 13. At this time, since the STA 101 has joined thewireless network 104 in the 2.4-GHz HT20, the STA 101 subsequentlyexecutes the processing in step S1204. That is to say, the STA 101transmits the TDLS Setup Response without performing Reassociationprocessing (S1502). The STA 103, upon receiving the TDLS Setup Response,transmits TDLS Setup Confirm as a response thereto (S1503). In thismanner, when the STA 101 has joined the wireless network 104 in the2.4-GHz HT20, the operation mode (frequency bandwidth) between the AP102 and the STA 101 is not changed.

After the operation mode is switched from the 2.4-GHz HT40 to the HT20by the above processing, if the direct connection is disconnected orswitching of the channel in the direct connection stops, the operationmode may be returned to the HT40 from the HT20. Processing in this casewill be described using FIG. 16.

FIG. 16 is a flowchart of processing of the communication mode decidingunit 1101 at the time when the STA 101 receives TDLS Teardown afterestablishing a direct connection to the STA 103. This processing isexecuted if the STA 101 receives the TDLS Setup Request from the STA103.

In this processing, the STA 101, upon receiving the TDLS Teardown fordisconnecting the direct connection from the STA 103 to which the STA101 has established a direct connection, determines whether or not thewireless network 104 supports the 2.4-GHz HT40 (S1601). Thisdetermination can be performed by checking an HT Capabilities elementcontained in a Beacon that is lastly received from the AP 102. Morespecifically, the STA 101 checks the value of Supported Channel WidthSet in an HT Capabilities Info field of the HT Capabilities element. Forexample, if the value is 1, the STA 101 can determine that the wirelessnetwork 104 supports both the HT20 and the HT40, and if the value is 0,the STA 101 can determine that the wireless network 104 supports onlythe HT20.

If the wireless network 104 supports the HT40 (YES in S1601), the STA101 transmits a Reassociation Request to the AP 102 in order to join thewireless network 104 with the HT40 (S1602). At this time, the SupportedChannel Width Set in the HT Capabilities Info field of the HTCapabilities element that is added to the Reassociation Request is setto 1. The STA 101, after transmitting the Reassociation Request to theAP 102, receives a Reassociation Response from the AP 102 (S1603). TheSTA 101 can thereby join the wireless network 104 with the 2.4-GHz HT40.On the other hand, if the wireless network 104 does not support the HT40(NO in S1601), switching from the HT20 to the HT40 is not performed, andthe STA 101 maintains the state of having joined the wireless network104 with the HT20.

Thus, when establishing a direct connection, the operation mode of aconnection to the AP is changed from the HT40 to the HT20. It is therebypossible to prevent occurrence of the OBSS Scan in the middle ofswitching the channel. Furthermore, if the established direct connectionis disconnected, the operation mode of the connection to the AP ischanged from the HT20 to the HT40. The STA 101 can thereby performhigh-speed communication with the AP 102 using the HT40 when a directconnection is not established.

In the above description, when the TDLS

Setup Request is received, the operation mode of a connection to awireless network is changed from the 2.4-GHz HT40 to the HT20, therebypreventing the OBSS Scan from being executed when channel switching ofTDLS occurs. However, any methods other than the above method may beemployed as long as the operation mode is changed from the 2.4-GHz HT40to the HT20 and the OBSS Scan is prevented from being executed whenchannel switching of TDLS occurs.

For example, not the TDLS Setup Request but other triggers may also beused with which a situation can be understood, e.g., with which it canbe determined that channel switching may possibly occur. As an example,when the TDLS Discovery Request or the TDLS Channel Switch Request isreceived, the operation mode of a connection to the wireless network maybe changed from the 2.4-GHz HT40 to the HT20. In the above mode, theoperation mode of the connection to the wireless network 104 is changedfrom the HT20 to the HT40 when the TDLS Teardown is received. However,the present invention is not limited to this method, and other modes inwhich the operation mode can be changed from the HT20 to the HT40 whenthe direct connection is disconnected (connection is released) may beused in the wireless network 104. For example, the operation mode of theconnection to the network may be changed from the HT20 to the HT40 afterthe TDLS Teardown is transmitted from the STA 101. Furthermore, theoperation mode of the connection to a network may be changed from theHT20 to the HT40 when the STA 101 or the STA 103 transmits the ChannelSwitch Response for switching the channel from the off-channel to thebase channel. That is to say, the operation mode of the connection tothe network may be returned to the HT40 when the channel is returned tothe base channel due to the finish of the communication over theswitched channel.

Processing Example 2

In this example, the STA 101 sets the operation mode of a connection tothe AP to the HT20 if TDLS has been activated, and sets the operationmode of the connection to the AP to the HT40 if TDLS has beeninactivated. It is thereby possible to prevent occurrence of the OBSSScan during channel switching of TDLS, and an unstable OBSS Scan is notexecuted.

In this example, the communication mode deciding unit 1101 is configuredto include a program for deciding, when joining a 2.4-GHz wirelessnetwork, to join the network with the HT20 or to be connected to theHT40 if TDLS is set by the UI control unit 1102. Since the OBSS Scandoes not need to be executed when joining a 5-GHz wireless network, inthis case, the STA 101 joins the wireless network with the HT40regardless of whether TDLS has been set. Processing of the communicationmode deciding unit 1101 is executed if TDLS is set by the UI controlunit 1102. FIG. 17 shows a flow of the processing executed by thecommunication mode deciding unit 1101 if TDLS is set by the UI controlunit 1102.

Upon TDLS being set, the communication mode deciding unit 1101determines whether TDLS has been activated or inactivated (S1701). Ifthe communication mode deciding unit 1101 determines that TDLS has beenactivated (YES in S1701), the communication mode deciding unit 1101 setsthe operation mode of the connection to the AP to the HT20 (S1702). Thatis to say, when joining the 2.4-GHz wireless network, the communicationmode deciding unit 1101 joins the network with the HT20 such that theSTA 101 does not execute the OBSS Scan. With this configuration, evenwhen the STA 101 joins the 2.4-GHz wireless network and a directconnection is established, the channel control does not becomecomplicated due to channel switching of TDLS.

On the other hand, if the communication mode deciding unit 1101determines that TDLS has been inactivated in step S1701 (NO in S1701),the communication mode deciding unit 1101 sets the operation mode of theconnection to the AP to the HT40 (S1703). That is to say, in this case,when joining the 2.4-GHz wireless network, the STA 101 joins the networkwith the HT40 and also executes the OBSS Scan. With this operation, whenTDLS has been inactivated and is unnecessary, the STA 101 joins thewireless network 104 with the HT40 in which higher-speed communicationcan be performed than with the HT20, and can thereby communicate, at ahigh speed, with a STA that has joined the wireless network 104.

FIGS. 18 and 19 are sequence charts showing processing flows in the casewhere the STA 101 joins a 2.4-GHz wireless network 104 that supports theHT40 when TDLS has been activated and inactivated, respectively.

In FIG. 18, TDLS is activated by the user through the UI control unit1102 (S1801). If TDLS is activated, the processing in step S1702 in FIG.17 is executed, and accordingly the STA 101 transmits, to the AP 102, anAssociation Request in which the HT20 is designated as the operationmode (S1802). That is to say, in this case, the Supported Channel WidthSet in the HT Capabilities Info field of the HT Capabilities element isset to 0. Thereafter, the STA 101 receives an Association Response,which is a response from the STA 103 (S1803). The STA 101 can therebyjoin the wireless network 104 with the HT20. In this case, the STA 101does not execute the OBSS Scan since the STA 101 has joined the wirelessnetwork with the HT20. If the STA 101 receives a TDLS Setup Request fromthe STA 103 at this time (S1804), the STA 101 responds thereto using aTDLS Setup Response with a Status Code that is SUCCESS, since TDLS isactive (S1805). The STA 103, upon receiving the TDLS Setup Response,transmits a TDLS Setup Confirm (S1806). Thus, a direct connectionbetween the STA 101 and the STA 103 can be established. Thereafter, whenthe STA 101 receives a TDLS Channel Switch Request from the STA 103,channel switching of TDLS is executed in conformity to the IEEE802.11specification.

In FIG. 19, TDLS is inactivated by the user through the UI control unit1102 (S1901). If TDLS is inactivated, the processing in step S1703 inFIG. 17 is executed, and accordingly the STA 101 transmits, to the AP102, an Association Request in which the HT40 is designated as theoperation mode (S1902). That is to say, in this case, the SupportedChannel Width Set with the HT Capabilities Info field of the HTCapabilities element is set to 1. Thereafter, the STA 101 receives anAssociation Response, which is a response from the STA 103 (S1903). TheSTA 101 can thereby join the wireless network 104 with the HT40. In thiscase, the STA 101 periodically executes the OBSS Scan since the STA 101has joined the wireless network with the HT40. If the STA 101 receives aTDLS Setup Request from the STA 103 at this time (S1904), the STA 101responds thereto using a TDLS Setup Response with a Status Code that isREFUSED, since TDLS is inactive (S1905). Thus, a direct connectionbetween the STA 101 and the STA 103 is not established, and channelswitching of TDLS is not performed either.

Although the response is made using the TDLS Setup Response with theStatus Code that is SUCCESS/REFUSED depending on whether TDLS has beenactivated/inactivated in the description of this example, the presentinvention is not limited thereto. For example, the STA 101 may beconfigured not to respond when TDLS is inactive. The STA 101 may also beconfigured not to respond to the TDLS Discovery Request. That is to say,in both cases, the STA 101 may be configured to operate as a STA thatdoes not support TDLS.

In this example, activation and inactivation of TDLS is set by the userthrough the UI. However, other methods may be used. Furthermore,activation/inactivation of channel switching of TDLS, rather thanactivation/inactivation of TDLS, may be set by the user. For example, asetting may be configured such that TDLS is active and channel switchingis inactive. Note that, in this case, the STA 101 cannot performoffloading of wireless channels but can communicate with the STA 103through a direct connection thereto without depending on the capabilityof the AP 102, and accordingly can perform efficient communication whenthe AP 102 has low capability.

Instead of the user explicitly setting activation and inactivation ofTDLS, a functional unit for configuring this setting may be providedwithin the STA 101. For example, a configuration may be employed inwhich the STA 101 activates TDLS if wireless LAN control is executed bya Wi-Fi Display application, and inactivates TDLS if wireless LANcontrol is executed by other applications. This is because, when TDLS isused with Wi-Fi Display, there is a possibility of occurrence oftransmission and reception of a large volume of data to/from a STA thatis a partner device to which a direct connection has been established,whereas communication with the AP is not considered to be important, insome cases. In such cases, the communication with the STA to which adirect connection has been established can be made more efficient if thecommunication with the AP is performed only with the HT20 and the OBSSScan is not executed instead. That is to say, interruption of videotransmission by means of Wi-Fi Display can be prevented by causing theOBSS Scan not to be executed.

Although this example has described the case of setting eitheractivation or inactivation of TDLS through the UI control unit 1102before being connected to the AP 102, activation and inactivation ofTDLS may be able to be set after the connection to the AP 102 isestablished. In this case, the STA 101 can switch the operation mode ofthe connection to the wireless network by transmitting the ReassociationRequest to the AP 102, as in the processing example 1 in Embodiment 2above.

Note that, in the present embodiment, since the OBSS Scan is notexecuted in a situation where channel switching may possibly occur, theoperation mode is changed from the 2.4-GHz HT40 to the HT20. However,the operation mode need only be changed such that the OBSS Scan is notexecuted, and other methods may be used. For example, the change of thejoining of a wireless network in conformity to IEEE802.11b orIEEE802.11g may be performed, rather than the change of the operationmode from the 2.4-GHz HT40 to the HT20. Furthermore, not a 2.4-GHz bandbut a 5-GHz band may be used.

According to the present invention, in a communication system where asecond connection is established based on a first connection, connectioncontrol can be performed in which the influence of the second connectionon the first connection is considered.

Other Embodiments

Embodiments of the present invention can also be realized by a computerof a system or apparatus that reads out and executes computer executableinstructions (e.g., one or more programs) recorded on a storage medium(which may also be referred to more fully as a ‘non-transitorycomputer-readable storage medium’) to perform the functions of one ormore of the above-described embodiments and/or that includes one or morecircuits (e.g., application specific integrated circuit (ASIC)) forperforming the functions of one or more of the above-describedembodiments, and by a method performed by the computer of the system orapparatus by, for example, reading out and executing the computerexecutable instructions from the storage medium to perform the functionsof one or more of the above-described embodiments and/or controlling theone or more circuits to perform the functions of one or more of theabove-described embodiments. The computer may comprise one or moreprocessors (e.g., central processing unit (CPU), micro processing unit(MPU)) and may include a network of separate computers or separateprocessors to read out and execute the computer executable instructions.The computer executable instructions may be provided to the computer,for example, from a network or the storage medium. The storage mediummay include, for example, one or more of a hard disk, a random-accessmemory (RAM), a read only memory (ROM), a storage of distributedcomputing systems, an optical disk (such as a compact disc (CD), digitalversatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, amemory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2014-036001, filed Feb. 26, 2014, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A communication device comprising: a connectionunit configured to establish a first connection to a first othercommunication device, establish, based on the first connection, a secondconnection to a second other communication device that is connected tothe first other communication device, while the first connection hasbeen established, and perform direct communication with the second othercommunication device using the second connection; a determination unitconfigured to determine whether an operation mode of the firstconnection is a mode in which a periodic search for another network isperformed while a network has been established by the first connection;and a control unit configured to, if the operation mode of the firstconnection is the mode in which the periodic search is performed,control the connection unit so as to restrict at least one ofestablishment of the second connection and switching of a channel in thesecond connection, while the first connection has been established. 2.The communication device according to claim 1, wherein, if the operationmode of the first connection is the mode in which the periodic search isperformed, the control unit restricts establishment of the secondconnection by the connection unit, by not responding to a search for apartner device for the second connection, the search being performed bythe second other communication device.
 3. The communication deviceaccording to claim 1, wherein, if the operation mode of the firstconnection is the mode in which the periodic search is performed, thecontrol unit restricts establishment of the second connection by theconnection unit, by not responding to a request to establish the secondconnection from the second other communication device, or by refusingthe request.
 4. The communication device according to claim 1, wherein,if the operation mode of the first connection is the mode in which theperiodic search is performed and the second connection has beenestablished, the control unit restricts switching of the channel in thesecond connection by the connection unit, by not responding to a requestto switch the channel in the second connection from the second othercommunication device, or by refusing the request.
 5. The communicationdevice according to claim 1, wherein the control unit restrictsestablishment of the second connection by the connection unit, by notresponding to a search for a partner device for the second connection,the search being performed by the second other communication device,during a time period during which the periodic search is performed inthe first connection.
 6. The communication device according to claim 1,wherein, if a request to establish the second connection is given fromthe second other communication device during a time period during whichthe periodic search is performed in the first connection, the controlunit restricts establishment of the second connection by the connectionunit, by not responding to the request or by refusing the request. 7.The communication device according to claim 1, wherein, if a request toswitch the channel in the second connection is given from the secondother communication device during a time period during which theperiodic search is performed in the first connection, the control unitrestricts switching of the channel in the second connection by theconnection unit, by not responding to the request or by refusing therequest.
 8. The communication device according to claim 1, wherein themode in which the periodic search is performed is an operation mode inwhich higher-speed communication can be performed than in a mode inwhich the periodic search is not performed.
 9. The communication deviceaccording to claim 1, wherein the periodic search is Overlapping BasicService Set (OBSS) scan in a wireless LAN that conforms to theIEEE802.11 standard series.
 10. A communication device comprising: aconnection unit configured to establish a first connection to a firstother communication device, establish, based on the first connection, asecond connection to a second other communication device that isconnected to the first other communication device, while the firstconnection has been established, and perform direct communication withthe second other communication device using the second connection; adetermination unit configured to determine whether an operation mode ofthe first connection is a first mode in which a periodic search foranother network is performed while a network has been established by thefirst connection; and a control unit configured to, if the operationmode of the first connection is the first mode, and establishment of thesecond connection or switching of a channel in the second connection isperformed, perform control such that the operation mode of the firstconnection is switched to a second mode in which the periodic search foranother network is not performed while the network has been establishedby the first connection.
 11. The communication device according to claim10, wherein the control unit switches the operation mode of the firstconnection from the first mode to the second mode by transmitting, tothe first other communication device, a signal for giving a request toswitch the operation mode.
 12. The communication device according toclaim 10, wherein, if the operation mode of the first connection is thefirst mode, the control unit performs control so as to switch theoperation mode of the first connection from the first mode to the secondmode in response to a search for a partner device for the secondconnection being performed by the second other communication device. 13.The communication device according to claim 10, wherein, if theoperation mode of the first connection is the first mode, the controlunit performs control so as to switch the operation mode of the firstconnection from the first mode to the second mode in response to arequest to establish the second connection being given by the secondother communication device.
 14. The communication device according toclaim 10, wherein, if the operation mode of the first connection is thefirst mode and the second connection has been established, the controlunit performs control so as to switch the operation mode of the firstconnection from the first mode to the second mode in response to arequest to switch the channel in the second connection being given bythe second other communication device.
 15. The communication deviceaccording to claim 10, wherein, if, after the operation mode of thefirst connection is switched from the first mode to the second mode, thesecond connection is disconnected or communication after the switchingof the channel in the second connection is finished, the control unitperforms control for switching the operation mode of the firstconnection from the second mode to the first mode.
 16. The communicationdevice according to claim 10, wherein, if the operation mode of thefirst connection is the first mode and a function related to the secondconnection in the connection unit is activated, the control unitperforms control for switching the operation mode of the firstconnection from the first mode to the second mode.
 17. The communicationdevice according to claim 16, wherein, if the function related to thesecond connection in the connection unit is inactivated after theoperation mode of the first connection is switched from the first modeto the second mode, the control unit performs control for switching theoperation mode of the first connection from the second mode to the firstmode.
 18. A method for controlling a communication device having aconnection unit configured to establish a first connection to a firstother communication device, establish, based on the first connection, asecond connection to a second other communication device that isconnected to the first other communication device, while the firstconnection has been established, and perform direct communication withthe second other communication device using the second connection, themethod comprising: determining whether an operation mode of the firstconnection is a mode in which a periodic search for another network isperformed while a network has been established by the first connection;and controlling the connection unit, if the operation mode of the firstconnection is the mode in which the periodic search is performed, so asto restrict at least one of establishment of the second connection andswitching of a channel in the second connection, while the firstconnection has been established.
 19. A method for controlling acommunication device having a connection unit configured to establish afirst connection to a first other communication device, establish, basedon the first connection, a second connection to a second othercommunication device that is connected to the first other communicationdevice, while the first connection has been established, and performdirect communication with the second other communication device usingthe second connection, the method comprising: determining whether anoperation mode of the first connection is a first mode in which aperiodic search for another network is performed while a network hasbeen established by the first connection; and performing control, if theoperation mode of the first connection is the first mode, andestablishment of the second connection or switching of a channel in thesecond connection is performed, such that the operation mode of thefirst connection is switched to a second mode in which the periodicsearch for another network is not performed while the network has beenestablished by the first connection.
 20. A non-transitorycomputer-readable storage medium storing a computer program for causinga computer provided in a communication device, which has a connectionunit configured to establish a first connection to a first othercommunication device, establish, based on the first connection, a secondconnection to a second other communication device that is connected tothe first other communication device, while the first connection hasbeen established, and perform direct communication with the second othercommunication device using the second connection, to execute:determining whether an operation mode of the first connection is a modein which a periodic search for another network is performed while anetwork has been established by the first connection; and controllingthe connection unit, if the operation mode of the first connection isthe mode in which the periodic search is performed, so as to restrict atleast one of establishment of the second connection and switching of achannel in the second connection, while the first connection has beenestablished.
 21. A non-transitory computer-readable storage mediumstoring a computer program for causing a computer provided in acommunication device, which has a connection unit configured toestablish a first connection to a first other communication device,establish, based on the first connection, a second connection to asecond other communication device that is connected to the first othercommunication device, while the first connection has been established,and perform direct communication with the second other communicationdevice using the second connection, to execute: determining whether anoperation mode of the first connection is a first mode in which aperiodic search for another network is performed while a network hasbeen established by the first connection; and performing control, if theoperation mode of the first connection is the first mode, andestablishment of the second connection or switching of a channel in thesecond connection is performed, such that the operation mode of thefirst connection is switched to a second mode in which the periodicsearch for another network is not performed while the network has beenestablished by the first connection.